[Interpreter] Basic flow control.

src/interpreter/bytecode-generator.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/interpreter/bytecode-generator.h"
 
 #include <stack>
 
 #include "src/compiler.h"
 #include "src/objects.h"
@@ skipping 100 matching lines @@
 void BytecodeGenerator::VisitExpressionStatement(ExpressionStatement* stmt) {
   Visit(stmt->expression());
 }
 
 
 void BytecodeGenerator::VisitEmptyStatement(EmptyStatement* stmt) {
   UNIMPLEMENTED();
 }
 
 
-void BytecodeGenerator::VisitIfStatement(IfStatement* stmt) { UNIMPLEMENTED(); }
+void BytecodeGenerator::VisitIfStatement(IfStatement* stmt) {
+  // TODO(oth): condition may need a ToBoolean cast - not if a
+  // sequence of test operations.

[rmcilroy, 2015/09/18 10:42:23]

Could you add the ToBoolean unconditionally for now (making the interpreter nop
this for now like the comparison ops is fine, but I'd like the bytecode
generated to be correct).

[oth, 2015/09/23 10:46:55]

Done.

+  // TODO(oth): spot easy cases if (true/1/false/0)?
+  BytecodeLabel else_start, else_end;
+  stmt->condition()->Accept(this);
+  builder().JumpIfFalse(&else_start);

[Benedikt Meurer, 2015/09/17 17:04:17]

Oh thank god, this is so much better to just materialize the stupid true/false
and compare against that in the if, than this micro optimization with the (most
often untagged) raw integer for the compare in fullcodegen. I think I'll try to
fix that in fullcodegen as well, so it is uniform. But this alone will avoid
some hairy tricks that we need to place to properly deopt to fullcodegen
currently.

+  Visit(stmt->then_statement());
+  builder().Jump(&else_end);
+  builder().Bind(&else_start);
+  Visit(stmt->else_statement());
+  builder().Bind(&else_end);
+}
 
 
 void BytecodeGenerator::VisitContinueStatement(ContinueStatement* stmt) {
   UNIMPLEMENTED();
 }
 
 
 void BytecodeGenerator::VisitBreakStatement(BreakStatement* stmt) {
   UNIMPLEMENTED();
 }
@@ skipping 313 matching lines @@
       UNIMPLEMENTED();
       break;
     default:
       VisitArithmeticExpression(binop);
       break;
   }
 }
 
 
 void BytecodeGenerator::VisitCompareOperation(CompareOperation* expr) {
-  UNIMPLEMENTED();
+  Token::Value op = expr->op();
+  Expression* left = expr->left();
+  Expression* right = expr->right();
+
+  TemporaryRegisterScope temporary_register_scope(&builder_);
+  Register temporary = temporary_register_scope.NewRegister();
+
+  Visit(left);
+  builder().StoreAccumulatorInRegister(temporary);
+  Visit(right);
+  // TODO(oth): ast-graph-builder has language_mode() option for LT/LE/etc.

[rmcilroy, 2015/09/18 10:42:23]

Could you pass the language mode here and do UNIMPLEMENTED for everything except
SLOPPY in bytecode-array-builder (like the Load/StoreICs) - just to make sure we
don't miss this later and have subtle bugs.

[oth, 2015/09/23 10:46:55]

Done.

+  builder().CompareOperation(op, temporary);
 }
 
 
 void BytecodeGenerator::VisitSpread(Spread* expr) { UNREACHABLE(); }
 
 
 void BytecodeGenerator::VisitEmptyParentheses(EmptyParentheses* expr) {
   UNREACHABLE();
 }
 
@@ skipping 34 matching lines @@
 }
 
 
 int BytecodeGenerator::feedback_index(FeedbackVectorICSlot slot) const {
   return info()->feedback_vector()->GetIndex(slot);
 }
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8